This disclosure relates to a gas turbine engine including, for example, compressor and turbine rotors assembled using a tie shaft connection.
Gas turbine engines include a compressor that compresses air and delivers it downstream to a combustion section. The air is mixed with fuel in the combustion section and combusted. Products of this combustion pass downstream over turbine rotors, causing the turbine rotors to rotate.
In one example arrangement, the compressor section is provided with a plurality of rotor stages, or rotor sections, arranged in a stack. Traditionally, these stages have been joined sequentially, one to another, into an inseparable assembly by welding, or into a separable assembly by bolting using bolt flanges, or other structure to receive the attachment bolts. Another joining approach uses a tie shaft and threaded member that cooperate with one another to clamp the rotor sections to one another.
The threaded member has a tendency to lift off of, or flare outward from, the tie shaft. This typically occurs at the base of the threaded member near where the axial load is applied to the stack. Lift off is due to the uneven axial loading of the threads. One solution has been to use a differing thread pitch between the tie shaft and the threaded member to achieve more even thread loading.